Bone turnover markers in clinical setting

Abstract

A variety of biochemical assays that reflects the activity of osteoblasts (the bone forming cells) and osteoclasts (the bone-resorbing cells) called bone turnover markers (BTM), have been developed for clinical use. Such tests do not establish the diagnosis of a disease, but rather they reflect the activity of the skeleton. BTM are non-invasive, comparatively inexpensive and, when applied and interpreted correctly, helpful tools in the diagnostic and therapeutic assessment of metabolic bone disease. With regard to osteoporosis, the usefulness of BTM remains controversial. Technological developments have greatly enhanced assay performance producing reliable and rapid assays with improved sensitivity and specificity. Problems in the measurement and interpretation of bone marker values continue to hamper the optimal utility of this clinical tool. Most of these difficulties originate from problems related to the handling and control of analytical and biological variability of bone marker measurements. These sources of variability can be substantial and need to be controlled.
Bone mineral density, in spite of its imperfections and inaccuracy, has been chosen as the goal standard for the diagnosis of osteoporosis and prediction of fractures.BTM do intend to diagnose osteoporosis or replace bone mass measurements. But, as complementary tools, they help in the management of osteoporosis in some circumstances: prediction of bone loss and fracture risk in untreated patients, identification of secondary causes of osteoporosis, monitoring response to treatment and documentation of adherence. BTMs may also be useful to decide when therapy should be recommenced after treatment holiday.